Studies on the mitogenic principle of the lipoprotein from the outer membrane of Escherichia coli

Lipoprotein, from the outer membrane of $\text{E. coli}$, and several derivatives were investigated for lymphocyte stimulating activity in different species. We could show that lipoprotein exhibits activity towards mouse and rat splenocytes and rabbit and bovine lymph node cells; human peripheral blood lymphocytes showed a weak but significant stimulation. Thymocytes of all species were also weakly activated. Altered molecular structures at the C-terminal end of lipoprotein had only small influence on activity, hydrolysis of N-terminal fatty acids abolished mitogenicity.